As disclosed in Sterling Drug's U.S. Pat. Nos. 3,753,993 (Lesher et al.), 3,907,808 (Lesher and Carabateas), and 4,118,557 (Lesher) and in copending applications Ser. No. 495,977 (Walter I), filed May 19, 1983; Ser. No. 497,026 (Ramachandran I) and Ser. No. 497,027 (Ramachandran II), both filed May 23, 1983; Ser. No. 511,831 (Ramachandran and Ranken), Ser. No. 511,832 (Ramachandran, Ranken, and Wiegand), and Ser. No. 511,913 (Ranken and Ramachandran), all filed July 8, 1963, it is known that antibacterial 1-alkyl-1,4-dihydro-4-oxo-7-pyridinyl-3-quinolinecarboxylic acids can be prepared from 4-(3-aminophenyl)pyridines.
From Mitscher et al., "Quinoline Antimicrobial Agents. 1. Versatile New Synthesis of 1-Alkyl-1,3-dihydro-4-oxo-3-quinolinecarboxylic Acids," Journal of Medicinal Chemistry, 1978, Vol. 21, No. 5, pp. 485-489, it is also known that antimicrobial agents related to the aforementioned bactericides can be prepared from the appropriate isatoic anhydrides. Copending applications Ser. No. 511,844 (Ranken and Walter), Ser. No. 511,854 (Ramachandran III), and Ser. No. 511,887 (Walter II), all filed July 8, 1983, and Ser. No. 523,462 (Walter and Ranken), filed Aug. 15, 1983, show that those bactericides can be prepared by a route similar to that employed by Mitscher et al.--a route utilizing a 2-amino-4-(4-pyridinyl)-benzoic acid as an intermediate.
Since each of the aforementioned processes for preparing 1-alkyl-1,4-dihydro-4-oxo-7-pyridinyl-3-quinolinecarboxylic acid bactericides is a complicated process involving the preparation of several intermediates, it is sometimes desirable to have different stages of the processes performed by different manufacturers. Versatility could thus be contributed by making it possible to cross over from one process to the other, i.e., convert an intermediate useful for preparing the bactericides by one technique to an intermediate suitable for preparing the bactericides by another technique. It would also be desirable to find an alternative technique of preparing 4-(3-aminophenyl)pyridines.